Stevia rebaudiana is a plant species in the sunflower (Asteraceae) family, which has naturally sweet leaves. The active compounds that impart the sweet flavor to stevia leaves are steviol glycosides. The most common steviol glycosides are stevioside and rebaudioside A, both of which have up to 250 to 400 times the sweetness of sugar. Stevioside tends to be more prevalent in unimproved lines of stevia leaves than rebaudioside A. The development of new varieties of Stevia rebaudiana with higher levels of rebaudioside A than stevioside is desirable for use as a sugar substitute.
The present invention relates to a new and distinct variety of Stevia rebaudiana, the ‘SW 129’ line, which has very sweet leaves with high levels of steviol glycosides and very low bitterness and aftertaste, excellent overwintering, high plant vigor, high leaf yield, and late flowering.
The ‘SW 129’ line was selected on Jun. 9, 2013, as a single plant in a population of recurrently selected Stevia rebaudiana, the population of which was originally grown from seed in an outdoor field in Chowchilla, Calif., USA, under natural lighting. The parentage of the ‘SW 129’ line is not known and population from which the ‘SW 129’ line was derived has no patented parental lineage. The plant that produced the ‘SW 129’ line was selected from its population based upon the following characteristics, which were measured and/or observed from Jun. 9, 2013, to October 2014.
Plant Vigor: The ‘SW 129’ line was found on Jun. 9, 2013, to have greater growth and survival in comparison to the majority of the plant population from which the line was derived.
Timing of Flowering: The ‘SW 129’ line was found in October 2013 to have later flowering (an advantage for leaf production) in comparison to the majority of the plant population from which the line was derived.
Leaf Taste: The leaves of the ‘SW 129’ line were found in August 2013 to have an excellent sweet taste in comparison to a majority of the plant population from which the line was derived and very little bitterness and aftertaste in comparison to most stevia varieties.
Rebaudioside A content: In 2014, the leaves of the ‘SW 129’ line were found to have a high percentage of rebaudioside A at 13.58% (Table 1), with 77.50% of the steviol glycosides in the leaves of the ‘SW 129’ line being attributed to rebaudioside A.
Ratio of rebaudioside A to stevioside content: The ratio of rebaudioside A to stevioside in the leaves of the ‘SW 129’ line was found to be high at 6.41 (Table 1).
Upon initial selection of the single plant in Chowchilla, Calif., the ‘SW 129’ line was asexually reproduced from rooted cuttings starting Jun. 11, 2013, in Ontario, Oreg. Plant yield and leaf quality of the ‘SW 129’ line were confirmed in April through October 2014 through replicated yield trials in the following three locations in the USA: Yuma, Ariz.; Indio, Calif.; and Ontario Oreg. At each of the three locations, the performance of the ‘SW 129’ line grown from cuttings was compared to seedlings of the ‘Candy’ line (Genesis Seed Ltd., Ashalin, Israel; not patented) grown from bulk commercial seed (“the check variety”). Table 1 compares various characteristics of an average sampling of leaves of the ‘SW 129’ line with an average sampling of leaves of the check variety.
TABLE 1SW 129Check Variety (‘Candy’)Percentage of Rebaudioside A13.58%6.85%Percentage of Stevioside 2.12%6.42%Percentage of total Steviol17.50%14.71% GlycosidesRatio of Rebaudioside A:Stevioside6.411.11Percentage of Rebaudioside A to 77.6%46.8%total Steviol Glycosides
The data in the foregoing table shows that in comparison to the check variety, the ‘SW 129’ line contained more rebaudioside A (13.58% vs. 6.85%); less stevioside (2.12% vs. 6.42%); more total steviol glycosides (17.50% vs. 14.71%); a higher rebaudioside A to stevioside ratio (6.41 vs. 1.11); and a higher percentage of rebaudioside A to total steviol glycosides (77.6% vs. 46.8%). In addition to the foregoing, the ‘SW 129’ line also produced 22% more leaf yield than the check variety with the ‘SW 129’ line producing 5178 lb. of leaf per acre per year versus 4232 lb. of leaf per acre per year for the check variety at Ontario, Oreg. Leaf yield results were averaged over two harvest strategies (one or two cuttings per year). The higher yield of the ‘SW 129’ line over the check variety in the Ontario, Oreg. location was due in part to low stand loss from Fusarium and other root diseases that reduced plant stand of the check variety. Overall leaf yield was higher in Ontario, Oreg. than in the hotter, drier climates of Yuma, Ariz. and Indio, Calif.